Here is the step by step instructions for canning salmon or tuna. I do both and trust me once you can your own tuna, you will never again eat regular tuna in the can at the grocery store.
Each step is very important, so to make sure you do not get sick or blow your kitchen up follow the instructions exactly.
Wash 24 jars in warm water or in dishwasher
Pack fish in jars and leave about 1/2 inch of head space
Add to top tuna or salmon 1/4 tea spoon canning salt and 1 teaspoon of lemon juice (do not add salt to any smoked fish, it has plenty from the brine)
Wipe the rim of the jar clean with a towel. My wife keeps the towels with the pressure cooker because the towels will stink even after you wash them.
Add 2 quarts of warm water into the pressure cooker and put a metal spacer that came with the pressure cooker on the bottom.
Place 8 lids into seperate pot of boiling water, not the rings just the lids. This softens the rubber seal of the lid. Only boil for about 2 minutes.
Put the lid onto the jar and hand tighten (not too tight just snug) the ring.
Put 8 jars in the bottom of the pressure cooker and layer with another metal spacer
Repeat up too three layers
Close lid and turn burner on high
Allow to cook on high with the steam cap off and bring to hard boil. Watch the steam vent tube when it begins steaming hard set timer for 10 minutes so it steams hard for 10 minutes
Place steam cap on vent tube and reduce heat a little. Watch for pressure to rise to 10 lbs.. Reduce heat to low and hold 10 lbs for 1 hour and 40 minutes (100 minutes). Try and hold pressure at 10 lbs and keep checking it because it will go up and down and will need adjusting.
After you reach the end of cooke time, turn off burner. DO NOT REMOVE THE HEAT VENT CAP OR LID. Allow the big vent tab to fall and pressure to go down to 0. This is very important!
Allow to cool down until little vent cap in front falls form the lack of pressure in the cooker. DO NOT REMOVE THE LID EARLY. YOU WILL BE BURNED SEVERELY IF YOU DO.
Remove lid but lift away as steam will be released into your face if you tilt it towards you.
Remove the jars to an old towel on counter top.
During and after cooling the jar lids will pop as they seal. When the jars are cool take a warm soapy washcloth and wipe the jars as they will be oily. The fish has a lot of oil in naturally. You can remove the rings to wipe the jars down.
Check the jars to make sure they have good seal by pressing on the lid, if it pops go ahead and eat it but do not store it! You must refrigerate and it will keep for a week.